When experiencing bugs with the xfce4-power-manager component, your way of helping things getting fixed is to report a bug about it in bugzilla.
Note: For this you will need to have/create an account.

• [Bug 15049] screen keeps black after lock screen (2019/01/16 13:32)
• [Bug 15012] feature: non-linear display brightness slider (2019/01/02 19:01)
• [Bug 14395] Slider for suspend and screensaver settings is missing some information (Xubuntu 18.04) (2018/12/07 04:17)
• [Bug 14864] my laptop never powers off (2018/11/10 10:55)
• [Bug 14845] Google Chrome inhibiting power management appearing twice (2018/11/05 18:19)
• [Bug 14716] Power manager is not blank screen (2018/11/04 22:49)
• [Bug 14819] power manager, display brightness, Fn keys cannot adjust brightness (2018/11/01 05:14)
• [Bug 14795] Battery indicator with a cross into it on Xubuntu 18.04.1 (Lenovo Miix 320 hybrid computer) (2018/10/25 13:26)
• [Bug 13530] xflock4 goes to suspend/hibernate on laptop lid closing, whereas lid closing is set to "switch off monitor" (2018/10/21 14:37)
• [Bug 14721] Automatically enable presentation mode when watching videos on YouTube? (2018/09/27 04:25)
• [Bug 14649] Display brightness label visible without dropdown (2018/09/27 03:13)
• [Bug 14687] Screen dims while playing when playing back video (2018/09/08 13:54)
• [Bug 11795] Disabling the automatic sleep causes data loss (2018/09/04 11:15)
• [Bug 12062] Screen brightness - increase number of increments (2018/08/29 09:22)
• [Bug 14616] Increase Display reduce after 120 seconds (2018/08/19 15:31)
• [Bug 14587] Undeclared dependency on gio-unix-2.0 (2018/08/08 00:00)
• [Bug 13761] Xfce4-power-manager does not catch lid events (2018/07/31 13:51)
• [Bug 14540] Suspend/Resumes on laptop lid close/open loads lockscreen after suspend showing desktop content for 1-2 seconds: potential security/privacy concerns (2018/07/24 08:59)
• [Bug 14541] Program terminated with signal SIGSEGV on battery empty (2018/07/17 11:58)
• [Bug 14441] Backlight increments - simple fix (2018/06/10 17:43)

If your bug/problem has not been reported before, report a new bug. Please ensure that you disclose any information that might be relevant for developers reading the bugreport, e.g. what distribution you're using, what package-version of xfce4-power-manager or related Xfce libraries etc. To report a new bug, go here.