You aren't running our distributed code - yours has been locally modified:
*** [ DIAGNOSING ]: Web version
[i] Web: v5.4 (https://discourse.pi-hole.net/t/how-do-i-update-pi-hole/249)
[i] Remotes: origin https://github.com/pi-hole/AdminLTE.git (fetch)
origin https://github.com/pi-hole/AdminLTE.git (push)
[i] Branch: master
[i] Commit: v5.4-0-g989e1ba-dirty
[i] Status: M .gitattributes
M .github/ISSUE_TEMPLATE.md
M .github/PULL_REQUEST_TEMPLATE.md
.....
You have three clients assigned to a different management group than the default group. The doubleclick regex is applied to group 0 (the default group) only. If the client from which you are able to load this domain is in the other group, the regex won't be applied to that client.
Thanks a lot. I totally missed that and I'm gonna edit my groups accordingly now. Also, I installed Pi-Hole from DietPi's dietpi-software cmd. Maybe that's why it looks like it has been modified.