Well, I tried the current 5.3.0 from the beta channel. In terms of ad blocking, nothing has changed… 5.3 still blocks fewer ads than 5.2.1 does. Additionally, updating to that 5.3.0 from the beta channel, new problems arose. First, the update did not maintain all my settings from 5.2.1, such as using DNS over HTTPS, and notifications (it turned off the Activity notification, and turned on the Icon Badge that I had turned off). The “worst” change was that when I turned the Activity notification back on, it didn’t, even after a restart.
One other thing… on my Android 9.0 tablet, I wanted to see if a clean install helped with ad blocking and Activity (it didn’t), but this caused a new problem… by default, without asking, Blokada was installed to my SD card. This resulted in being unable to automatically restart the app after restarting the tablet. The VPN always on setting did not hold. I moved Blokada to internal storage and that problem went away. Surprisingly, when I installed (clean) 5.2.1, the same problem occured.
I can suggest a cause… 5.3 installed with backups on by default, which I turned off. I suspect that, when I did a clean install on 5.2.1, 5.3 had created a backup which stayed after I turned that “feature” off, and 5.2.1 used that backup to install where 5.3 did, on the SD card. I had to move 5.2.1 to get the VPN setting to stick there, too.