Welcome to blokada! I see you have tried some of the troubleshooting steps (excluding blokada from battery optimization, turning keep alive on)-here are more to check:
If you have a dns on in blokada disable it-this is to ensure that the problem is not associated with the dns.
Have you turned off Private DNS in your phone settings? If not please make sure it is set to off.
In your phone settings set blokada as the always on vpn (as well as having it on within the blokada app itself).
To solve the autostart issue, have you rebooted your phone after selecting "always on "vpn in blokada? That typically works- blokada has had some issues with starting on boot in android pie.
Hmm u want to unhide the keep alive notification? Usually people want to do the opposite XD. To change the notification from silent to alert varies on each phone. On my phone you hold down the notification to change its alert settings-maybe that will work for yours.
Please report back and let us know if this works for you