BTS-06 Bluetooth speaker

I have a shower speaker BTS-06 it connects to the iPhone XR and iPad fine but will not connect to the iPhone 12. I have tried all the tips suggested on various posts here, have the latest software but nothing works. The phone connects to all other Bluetooth devices though and other devices connect to the speaker fine.

It’s so frustrating and I’m beginning to regret upgrading from the XR to the 12 not seen much difference other than the 12 doesn’t like the Bluetooth shower speaker and it’s costing more money. Should have kept the XR and gone to a sim only contract.