I’ve found a single occurence of Failed to find block filter in index from December 2024 on the blockfilterindex=1 node. This seems to be a floresta peer=1580012 that (at least back then) would request a getcfilters for a block we hadn’t connected and neither inv’ed to it yet.
2024-12-21T19:45:35.353185Z [msghand] [net_processing.cpp:3580] [ProcessMessage] [net] receive version message: /Floresta:0.7.0/: version 70016, blocks=0, us=X, txrelay=0, peer=1580012, peeraddr=Y
...
2024-12-21T22:52:54.450806Z [msghand] [net_processing.cpp:4330] [ProcessMessage] Saw new cmpctblock header hash=000000000000000000009f27b05ec8d4a533b8ad61f670b8441e3a656a2ad084 peer=Z
2024-12-21T22:52:54.558481Z [msghand] [blockencodings.cpp:220] [FillBlock] [cmpctblock] Successfully reconstructed block 000000000000000000009f27b05ec8d4a533b8ad61f670b8441e3a656a2ad084 with 1 txn prefilled, 2081 txn from mempool (incl at least 16 from extra pool) and 28 txn requested
...
2024-12-21T22:52:55.700045Z [scheduler] [validationinterface.cpp:215] [operator()] [validation] BlockConnected: block hash=000000000000000000009f27b05ec8d4a533b8ad61f670b8441e3a656a2ad084 block height=875798
2024-12-21T22:52:55.704025Z [msghand] [net_processing.cpp:3382] [ProcessMessage] [net] received: getcfilters (37 bytes) peer=1580012
2024-12-21T22:52:55.704055Z [msghand] [net_processing.cpp:3183] [ProcessGetCFilters] [net] Failed to find block filter in index: filter_type=basic, start_height=875798, stop_hash=000000000000000000009f27b05ec8d4a533b8ad61f670b8441e3a656a2ad084
2024-12-21T22:52:55.713134Z [scheduler] [validationinterface.cpp:179] [operator()] [validation] UpdatedBlockTip: new block hash=000000000000000000009f27b05ec8d4a533b8ad61f670b8441e3a656a2ad084 fork block hash=00000000000000000000f9038e041a74a5b69790258b1ed9c17573e161bbeca2 (in IBD=false)
...
2024-12-21T22:52:55.713346Z [msghand] [net_processing.cpp:5651] [SendMessages] [net] SendMessages: sending inv peer=1580012 hash=000000000000000000009f27b05ec8d4a533b8ad61f670b8441e3a656a2ad084