[Xiaomi Mi A1 ROMs, Kernels, Recoveries, & Other De] cor35vet:
Yeah, I installed the 9.0 December one from here: https://xdaforums.com/mi-a1/themes/twrp-baseband-modem-april-stock-rom-t3777901

But now another issue revealed itself: Calls have no audio, I can't hear anything and the other person can't hear me either.

On Signal Private Messenger calls I can hear the other person but they can't hear me, however I can record voice messages fine?!

12-26 19:42:06.453 11577 11616 D voice : voice_start_usecase: enter usecase:voicemmode1-call
12-26 19:42:06.453 11577 11616 D audio_hw_primary: select_devices for use case (voicemmode1-call)
12-26 19:42:06.453 11577 11616 D audio_hw_primary: select_devices: out_snd_device(16: voice-handset) in_snd_device(95: voice-dmic-ef)
12-26 19:42:06.453 11577 11616 I msm8916_platform: platform_check_and_set_codec_backend_cfg:becf: afe: bitwidth 16, samplerate 48000 channels 2, backend_idx 0 usecase = 36 device (voice-handset)
12-26 19:42:06.453 11577 11616 D msm8916_platform: platform_split_snd_device: snd_device(16) num devices(1) new_snd_devices(0)
12-26 19:42:06.453 11577 11616 I msm8916_platform: platform_check_and_set_codec_backend_cfg: becf: new_snd_devices[0] is voice-handset
12-26 19:42:06.453 11577 11616 I msm8916_platform: platform_check_codec_backend_cfg:becf: afe: Codec selected backend: 0 current bit width: 16 sample rate: 48000 channels: 2 usecase 36 device (voice-handset)
12-26 19:42:06.453 11577 11616 W msm8916_platform: platform_check_codec_backend_cfg:becf: afe:Use default bw and sr for voice/voip calls
12-26 19:42:06.453 11577 11616 D msm8916_platform: platform_check_codec_backend_cfg:becf: afe: playback on codec device not supporting native playback set default Sample Rate(48k)
12-26 19:42:06.453 11577 11616 D msm8916_platform: platform_check_codec_backend_cfg:becf: afe: only 48KHZ sample rate is supported Configure afe to default Sample Rate(48k)
12-26 19:42:06.453 11577 11616 I msm8916_platform: platform_check_codec_backend_cfg:becf: afe: Codec selected backend: 0 updated bit width: 16 sample rate: 48000 channels: 2
12-26 19:42:06.453 11577 11616 D audio_hw_primary: check_usecases_codec_backend:becf: force routing 0
12-26 19:42:06.453 11577 11616 E msm8916_platform: platform_check_backends_match: Invalid snd_device =
12-26 19:42:06.453 11577 11616 D audio_hw_primary: check_usecases_codec_backend:becf: (65) check_usecases curr device: voice-handset, usecase device: backends match 0
12-26 19:42:06.453 11577 11616 D audio_hw_primary: check_usecases_codec_backend:becf: check_usecases num.of Usecases to switch 0
12-26 19:42:06.453 11577 11616 D hardware_info: hw_info_append_hw_type : device_name = voice-handset
12-26 19:42:06.453 11577 11616 D msm8916_platform: platform_split_snd_device: snd_device(16) num devices(0) new_snd_devices(0)
12-26 19:42:06.453 11577 11616 D audio_hw_primary: enable_snd_device: snd_device(16: voice-handset)
12-26 19:42:06.453 11577 11616 I soundtrigger: audio_extn_sound_trigger_update_device_status: device 0x10 of type 0 for Event 1, with Raise=0
12-26 19:42:06.453 11577 11616 D audio_route: Apply path: voice-handset

Only meaningful error I found ^

I forgot to mention that I upgraded from Lineage 15.1 to 16.0 by deleting system and cache and keeping data.

I definitely don't want to set up my whole phone again so I'll restore my 15.1 backup for now.