This could be similar to Bug #1768352, but I noticed that with Mate 21.10 (upgraded from 20.04) the lock screen gets bypassed on wake. I suspend the laptop while connected to an external display, on wake from the laptop panel (disconnect the external monitor) the lock screen is bypassed. It takes a minute and boots right into the desktop.
If it helps the external monitor is a full HD panel while the laptop has a strange resolution of 3x2. I think while the xserver tries to draw everything in the different resolution it skips the lock screen. Normal just lock or power throttle all work fine.
Hardware used: Microsoft Surface Laptop Go.
joe@mateLP:~$ neofetch
`:+shmNNMMNNmhs+:` joe@mateLP
.odMMMMMMMMMMMMMMMMMMdo. ----------
/dMMMMMMMMMMMMMMMmMMMMMMMMd/ OS: Ubuntu MATE 21.10 x86_64
:mMMMMMMMMMMMMNNNNM/`/yNMMMMMMm: Host: Surface Laptop Go 124I:00057T:
`yMMMMMMMMMms:..-::oM: -omMMMMMy` Kernel: 5.13.0-22-generic
`dMMMMMMMMy-.odNMMMMMM: -odMMMMMMd` Uptime: 14 hours, 26 mins
hMMMMMMMm-.hMMy/....+M:`/yNm+mMMMMMMMh Packages: 2232 (dpkg), 5 (flatpak),
/MMMMNmMN-:NMy`-yNMMMMMmNyyMN:`dMMMMMMM/ Shell: bash 5.1.8
hMMMMm -odMMh`sMMMMMMMMMMs sMN..MMMMMMMh Resolution: 1536x1024
NMMMMm `/yNMMMMMMMMMMMM: MM+ mMMMMMMN DE: MATE 1.26.0
NMMMMm `/yNMMMMMMMMMMMM: MM+ mMMMMMMN WM: Metacity (Marco)
hMMMMm -odMMh sMMMMMMMMMMs oMN..MMMMMMMh Theme: Yaru-MATE-dark [GTK2/3]
/MMMMNNMN-:NMy`-yNMMMMMNNsyMN:`dMMMMMMM/ Icons: Ambiant-MATE [GTK2/3]
hMMMMMMMm-.hMMy/....+M:.+hNd+mMMMMMMMh Terminal: mate-terminal
`dMMMMMMMMy-.odNMMMMMM: :smMMMMMMd` Terminal Font: Ubuntu Mono 14
yMMMMMMMMMms/..-::oM: .+dMMMMMy CPU: Intel i5-1035G1 (8) @ 3.600GHz
:mMMMMMMMMMMMMNNNNM: :smMMMMMMm: GPU: Intel Iris Plus Graphics G1
/dMMMMMMMMMMMMMMMdNMMMMMMMd/ Memory: 3958MiB / 7545MiB
.odMMMMMMMMMMMMMMMMMMdo.
`:+shmNNMMNNmhs+:`
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu71
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: MATE
DistroRelease: Ubuntu 21.10
InstallationDate: Installed on 2021-12-13 (5 days ago)
InstallationMedia: Ubuntu-MATE 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819.1)
Package: mate-screensaver 1.26.0-0ubuntu1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 5.13.0-22.22-generic 5.13.19
Tags: impish
Uname: Linux 5.13.0-22-generic x86_64
UpgradeStatus: Upgraded to impish on 2021-12-14 (5 days ago)
UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo
_MarkForUpload: True
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu71
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: MATE
DistroRelease: Ubuntu 21.10
InstallationDate: Installed on 2021-12-13 (46 days ago)
InstallationMedia: Ubuntu-MATE 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819.1)
Package: mate-screensaver 1.26.0-0ubuntu1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 5.13.0-27.29-generic 5.13.19
Tags: impish
Uname: Linux 5.13.0-27-generic x86_64
UpgradeStatus: Upgraded to impish on 2021-12-14 (45 days ago)
UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo
_MarkForUpload: True
A quick update, I found that this behavior actually depends more on the way the suspend is set. Seems that entering suspend with the indicator applet doesn't enable the lock screen. However, if done from Brisk Menu Launcher the lock screen is set. Perhaps the behavior from the Brisk Menu Launcher can be sync'd to the Indicator applet. Indicator applet version is 1.26.0, Brisk Menu Launcher version is 0.6.2. Thank you.