r/androidapps pop up on restart from sleep - why?

Something has changed in the past week or two, and I am not aware of anything I've done which has caused it -
Shortly after restarting from sleep my laptop sometimes shows an on screen pop-up for a few seconds which is headed with r/androidapps and below that heading is a different query every time.
For instance, I have a screen grab of one which says "is there any way to open an app shortcut instantly while using other apps?".

Since early this year (2021) My laptop has been running without pop-ups appearing, and "ubuntu" updates regularly.

Ubuntu 20.04.3 LTS (Focal Fossa) 64 bit
Kernel linux 5.4.0-88-generic x86_64
MATE 1.24.0

I am using Firefox 93.0 (64 bit)

I have run

sudo apt update
sudo apt --fix-broken install
sudo apt autoremove

without any change in the pop-ups.

The laptop occasionally wakes without the wi-fi active and on one occasion when I re-enabled the wi-fi the pop-appeared as soon as the wi-fi icon in the status bar showed the connection restored.

I have looked at syslog shortly after a "pop up" has happened (09:08 this morning in the bit of syslog below), but don't have the knowledge or skill to understand - here's what I think is the relevant chunk:

Oct 21 09:07:26 John-Acer-5738 whoopsie[1009]: [09:07:26] online
Oct 21 09:07:37 John-Acer-5738 systemd[1]: NetworkManager-dispatcher.service: Succeeded.
Oct 21 09:07:41 John-Acer-5738 systemd[1]: man-db.service: Succeeded.
Oct 21 09:07:41 John-Acer-5738 systemd[1]: Finished Daily man-db regeneration.
Oct 21 09:07:43 John-Acer-5738 dbus-daemon[784]: [system] Activating via systemd: service name='org.freedesktop.PackageKit' unit='packagekit.service' requested by ':1.480' (uid=0 pid=57894 comm="/usr/bin/gdbus call --system --dest org.freedeskto" label="unconfined")
Oct 21 09:07:43 John-Acer-5738 systemd[1]: Starting PackageKit Daemon...
Oct 21 09:07:44 John-Acer-5738 PackageKit: daemon start
Oct 21 09:07:50 John-Acer-5738 dbus-daemon[784]: [system] Successfully activated service 'org.freedesktop.PackageKit'
Oct 21 09:07:50 John-Acer-5738 systemd[1]: Started PackageKit Daemon.
Oct 21 09:07:50 John-Acer-5738 kernel: [72598.927934] [UFW BLOCK] IN=wlp4s0 OUT= MAC=01:00:5e:00:00:01:58:90:43:3c:18:c1:08:00 SRC=192.168.1.254 DST=224.0.0.1 LEN=36 TOS=0x00 PREC=0x00 TTL=1 ID=0 DF PROTO=2
Oct 21 09:07:55 John-Acer-5738 dbus-daemon[1246]: [session uid=1000 pid=1246] Activating service name='org.freedesktop.Notifications' requested by ':1.66' (uid=1000 pid=1885 comm="/usr/lib/firefox/firefox " label="unconfined")
Oct 21 09:07:57 John-Acer-5738 dbus-daemon[1246]: [session uid=1000 pid=1246] Successfully activated service 'org.freedesktop.Notifications'
Oct 21 09:08:26 John-Acer-5738 dbus-daemon[784]: [system] Activating via systemd: service name='org.freedesktop.hostname1' unit='dbus-org.freedesktop.hostname1.service' requested by ':1.482' (uid=1000 pid=57930 comm="mate-screenshot " label="unconfined")
Oct 21 09:08:27 John-Acer-5738 systemd[1]: Starting Hostname Service...
Oct 21 09:08:30 John-Acer-5738 dbus-daemon[784]: [system] Successfully activated service 'org.freedesktop.hostname1'
Oct 21 09:08:30 John-Acer-5738 systemd[1]: Started Hostname Service.
Oct 21 09:09:00 John-Acer-5738 systemd[1]: systemd-hostnamed.service: Succeeded.
Oct 21 09:09:14 John-Acer-5738 systemd[1]: apt-daily.service: Succeeded.
Oct 21 09:09:14 John-Acer-5738 systemd[1]: Finished Daily apt download activities.
Oct 21 09:09:14 John-Acer-5738 systemd[1]: Starting Daily apt upgrade and clean activities...

Can you tell me what is causing the pop-up, and is it something I should be (more) worried about?

Regards,

John H