1.21.3 server crash on player join

[GunnyWaffle]

In testing the new 1.21.3 version of this mod, the following error occurs when a player joins the server. This crashes the server, taking it offline immediately.

[19:35:00] [Server thread/ERROR]: Encountered an unexpected exception
java.lang.NoSuchMethodError: 'net.minecraft.class_2168 net.minecraft.class_1297.method_5671()'
        at knot/eu.pb4.placeholders.api.PlaceholderContext.of(PlaceholderContext.java:106) ~[placeholder-api-2.4.0+1.21-c8d8bd1e7171f894.jar:?]
        at knot/eu.pb4.placeholders.api.PlaceholderContext.of(PlaceholderContext.java:102) ~[placeholder-api-2.4.0+1.21-c8d8bd1e7171f894.jar:?]
        at knot/io.github.polymeta.serverlinkssender.config.BaseConfig.lambda$buildPacketContents$3(BaseConfig.java:53) ~[ServerLinksSender-1.0.1.jar:?]
        at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[?:?]
        at java.base/java.util.HashMap$EntrySpliterator.forEachRemaining(HashMap.java:1858) ~[?:?]
        at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[?:?]
        at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[?:?]
        at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921) ~[?:?]
        at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?]
        at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682) ~[?:?]
        at knot/io.github.polymeta.serverlinkssender.config.BaseConfig.buildPacketContents(BaseConfig.java:54) ~[ServerLinksSender-1.0.1.jar:?]
        at knot/io.github.polymeta.serverlinkssender.ServerLinksSender.lambda$onInitialize$7(ServerLinksSender.java:110) ~[ServerLinksSender-1.0.1.jar:?]
        at knot/net.fabricmc.fabric.api.networking.v1.ServerPlayConnectionEvents.lambda$static$2(ServerPlayConnectionEvents.java:48) ~[fabric-networking-api-v1-4.3.4+fd37071f40-91fbb53e08def3ea.jar:?]
        at knot/net.fabricmc.fabric.impl.networking.server.ServerPlayNetworkAddon.onClientReady(ServerPlayNetworkAddon.java:63) ~[fabric-networking-api-v1-4.3.4+fd37071f40-91fbb53e08def3ea.jar:?]
        at knot/net.minecraft.class_3324.handler$zna000$fabric-networking-api-v1$handlePlayerConnection(class_3324.java:3988) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_3324.method_14570(class_3324.java:203) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_8610.method_52408(class_8610.java:152) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_8736.method_53043(class_8736.java:22) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_8736.method_11054(class_8736.java:8) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_2600.method_11072(class_2600.java:27) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_3738.run(class_3738.java:18) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_1255.method_18859(class_1255.java:164) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_4093.method_18859(class_4093.java:23) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_24306(MinecraftServer.java:889) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_18859(MinecraftServer.java:180) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_1255.method_16075(class_1255.java:138) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_20415(MinecraftServer.java:871) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_16075(MinecraftServer.java:865) ~[server-intermediary.jar:?]
        at knot/net.minecraft.class_1255.method_18857(class_1255.java:147) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_18857(MinecraftServer.java:829) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_16208(MinecraftServer.java:836) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_29741(MinecraftServer.java:719) ~[server-intermediary.jar:?]
        at knot/net.minecraft.server.MinecraftServer.method_29739(MinecraftServer.java:292) ~[server-intermediary.jar:?]
        at java.base/java.lang.Thread.run(Thread.java:1583) [?:?]