Just feeding back that the TVHeadend Client addon gets disabled after the compatibility check when trying to upgrade from LibreELEC-RPi4.arm-11.0-nightly-20211006-9fefbf7 to the last two nightlies:
LibreELEC-RPi4.arm-11.0-nightly-20211008-8696f6d
LibreELEC-RPi4.arm-11.0-nightly-20211007-a405b57
LE 11.00 nightlies have been working great for me otherwise. Very smooth rendering of IPTV streams and other media. Colours are also better for me than with 19.1 stable.
Rolling back to LibreELEC-RPi4.arm-11.0-nightly-20211006-9fefbf7 fixed the issue on both upgrade attempts.
And a big thanks for all your great work team Libreelec.