"Non-mandatory-script-verify-flag (Invalid Schnorr Signature)" on testnet

[Bitcoin]

"Non-mandatory-script-verify-flag (Invalid Schnorr Signature)" on testnet

I'm using the FROST algorithm to create a threshold signature for some taproot output (using this code).

When I tried using it on the testnet, it works most of the time but from time to time I would randomly get the above error message. Any idea what could be causing this?

Edit: adding an example where the error happened:

$ curl -u "$bitcoinauth" -d '{"jsonrpc": "1.0", "id": "curltest", "method": "createrawtransaction", "params": [[{"txid":"861840c7ddadf2c519f9906e575ff95a08bfca544d56833286dcada5d546fa9d","vout": 0, "sequence": 4294967295}], [{"tb1pfnh0sgankkq2wjhx2u33pe2vwwyg5saec7q8x0jl6r2zhqzcwm6ql36j2u": "0.00006000"}, {"data": "44701c002b2394a6d85ad03d0a7bd6c4680498573cc7bee396ac95a990370cc7"}]]}'  -H 'content-type: text/plain;' http://127.0.0.1:18332/
{"result":"02000000019dfa46d5a5addc863283564d54cabf085af95f576e90f919c5f2adddc74018860000000000ffffffff0270170000000000002251204ceef823b3b580a74ae6572310e54c73888a43b9c780733e5fd0d42b805876f40000000000000000226a2044701c002b2394a6d85ad03d0a7bd6c4680498573cc7bee396ac95a990370cc700000000","error":null,"id":"curltest"}
$ curl -u "$bitcoinauth" -d '{"jsonrpc": "1.0", "id":"curltest", "method": "sendrawtransaction", "params": ["020000000001019dfa46d5a5addc863283564d54cabf085af95f576e90f919c5f2adddc74018860000000000ffffffff0270170000000000002251204ceef823b3b580a74ae6572310e54c73888a43b9c780733e5fd0d42b805876f40000000000000000226a2044701c002b2394a6d85ad03d0a7bd6c4680498573cc7bee396ac95a990370cc701406da7fa1af2e75daaefc37d1c493d1a24a9e05283a47dbb3e9ccd3232ce0f0becbe425d1f7276dc42a29741fa727a0f7370bde939056c5fec72b399267ca1904f00000000"]}' -H 'content-type: text/plain;' http://127.0.0.1:18332/
{"result":null,"error":{"code":-26,"message":"non-mandatory-script-verify-flag (Invalid Schnorr signature)"},"id":"curltest"}

Code used to create the transaction: https://github.com/filecoin-project/eudico/blob/bitcoin-testnet/chain/checkpointing/sub.go#L697-L757

Source: "Non-mandatory-script-verify-flag (Invalid Schnorr Signature)" on testnet