The author of the L_Ender's Cataclysm mod has no comments on CurseForge or the opportunity to write about the error. There is only a Discord channel, maybe there is a Feedback.

Is this a bug with his mod? Should I write to him?

[21:32:53] [Worker-ResourceReload-11/ERROR]: [Load My Fucking Tags] Couldn't load certain entries with the tag cataclysm:ancient_remnant_target: minecraft:sniffer (from L_Enders_Cataclysm-1.88 -1.19.2.jar)
10239 | [21:32:53] [Worker-ResourceReload-11/ERROR]: [Load My Fucking Tags] Couldn't load certain entries with the tag cataclysm:modern_remnant_target: minecraft:sniffer (from L_Enders_Cataclysm-1.88 -1.19.2.jar)

Here is info about what exactly means. It is most likely a bug with the mod but it is not harmful. The modpack being used added LMFT to prevent bigger issues so you can just ignore the error for now.