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 15197] [patch] xfpm-backlight-helper reads wrong file for brightness (2019/03/14 21:02)
• [Bug 15180] screen remains blank on any activity (2019/03/08 17:13)
• [Bug 15162] Presentation Mode to inhibit suspend on lid close? (2019/03/01 12:30)
• [Bug 15151] Unable to override logind lid open/close handlers (2019/02/20 19:06)
• [Bug 14395] Slider for suspend and screensaver settings is missing some information (Xubuntu 18.04) (2019/02/16 02:18)
• [Bug 15134] laptop backlight adjustment mismatch (2019/02/11 18:12)
• [Bug 15129] Display power management sliders should not require 1 minute separation between blank/put to sleep/switch off (2019/02/08 10:35)
• [Bug 15111] xfce4-power-manager blocks screensaver (2019/02/02 21:15)
• [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 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)

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.