I have same issue (or maybe it’s a feature?) as this Motorola user: https://forums.lenovo.com/t5/moto-g-stylus-5G-2022/Bluetooth-transfer-file-names-Android-13-update/m-p/5253320 .
When my Fairphone receives files via bluetooth from my older phone (no fancy applications or “nearby sharing”, just plain Bluetooth file transfer), it appends timestamp to the filename, formatted like this: “_hhmmss” (for example “file.png” → “file_213700.png”). It happens even if there is no possible filename collision in my Fairphone. I don’t think I’ve ever seen such behavior before (but then again, it’s just my third Android phone).
It’s got really a big deal, but it’s a bit annoying. Do you also have same behavior?