Celtic have lost 380 appearances to injury this season across the squad. On average 6.7 players are unavailable each game due to injury.
Ever Available
Only 5 players in the squad have been avoided missing games due to injury.

And one of these is a goalkeeper (tends to have less injuries), two are only recently joined on loan (Toljan and Weah) and one is a young prospect (Johnston).
Of the experience out field players only Sinclair has avoided injury this season.
Injury Table

Four players have missed over half the season. Three (Bitton, Arzani and Kouassi) due to cruciate knee injuries and one (Griffiths) for a variety of reasons mainly his own mental well-being.
Every senior player in the squad has missed at least 2 matches apart from Forrest and Sinclair. Which is surprising as they play in wide attacking positions and are usually heavily tackled.
Thirteen players have missed over 10 games and a full team plus one sub (12 players) have missed at least 25% of the matches.
Celtic are on course for a 63-match season. This follows 61 and 59 in Rodgers’ previous seasons. With European Qualifiers starting in July, preseason training starts early June. Celtic players have had 3 to 4 weeks off in the summer typically. Less if they have appeared in International summer tournaments.
This summer looks like being the same but at least there is no major International tournament.
Player health management needs to be a priority.