For nigh on three weeks my 2017 MacBook Pro was unusable because only one of two Thunderbolt 3 ports was working and intermittently at that. This meant it couldn't be charged or backed up.
The day before its replacement (M1 MacBook Air) arrived I was surprised that I was able to charge it fully and then make a clone & a Time Machine backup without further charging needed. This allowed me to set up the new M1 MacBook Air via Migration Assistant from the Time Machine backup.
The for the following 10 days the MB Pro was sick again, refusing to recognise any power or drives connected to it.
Suddenly it's all sweetness and light. Both Thunderbolt ports work and I've been able to install a basic version of Monterey on it, with only a couple of utility apps & Carbon Copy Cloner added to the standard Apple apps.