This is a well known bug in bedrock edition.
If the repeater was activated by another pure redstone component being
ticked, then the delay will be correct. However, if it was activated
by a world change (lever, piston modifying a circuit, pressure plates,
buttons, etc) then the repeater will output a signal 1 tick too fast.
It effects many (all?) versions of the game and judging by some of their comments, it seems they know why it is happening but can't fix it without restructuring a significant portion of the game. I can confirm that does not happen in my java edition of the game.
https://bugs.mojang.com/browse/MCPE-15793
They list all the effected versions of the game here.
1.17.10, 1.16.200.57 Beta, 1.16.100.58 Beta, 1.16.100.56 Beta, 1.16.100.55 Beta, 1.15.0.8 RTX Beta, 1.16.0.63 Beta, 1.16.0.61 Beta, 1.15.0.53 Beta, 1.15.0.51 Beta, 1.14.30.51 Beta, 1.14.2.51 Beta, 1.14.2.50 Beta, 1.14.0.51 Beta, 1.13.3, 1.14.0.4 Beta, 1.13.1, 1.14.1 Hotfix, 1.14.0.3 Beta, 1.14.0.2 Beta, 1.14.0.1 Beta, 1.13.0.18 Beta, 1.13.0.17 Beta, 1.13.0.16 Beta, 1.13.0.15 Beta, 1.13.0.9 Beta, 1.13.0.6 Beta, 1.12.0.2 Beta, 0.15.0, 0.15.2, 0.15.4, 0.15.10, 0.15.90.8, 0.16.0, 0.16.1, 0.17.0.1, 0.16.2, 1.0.0.0, 1.0.0.1, 1.0.0.7, 1.0.0, 1.0.2, 1.0.3, 1.0.4.0, 1.0.4.1, 1.0.4.11, 1.0.5.13, 1.0.6.0, 1.0.5.54, 1.1.0.0, 1.0.6.52, 1.1.0.4, 1.1.0.5, 1.0.7.0, 1.1.0.9, 1.1.0.55, 1.1.1.0, 1.1.1.51, 1.1.2.50, 1.1.3.1, 1.1.5.0, 1.2.0.25, 1.2.0.31, 1.2.3.6, 1.2.5.12, 1.2.6.2, 1.2.5.52, 1.2.6.60, 1.2.9.1, 1.2.10.1, 1.2.10.2, 1.2.15.01, 1.2.16.3, 1.5.0.0, 1.4.0.5, 1.5.0.7, 1.4.2.0, 1.5.0.14, 1.6.0.6, 1.7.0.9 Beta, 1.9.0, 1.10.0.4 Beta, 1.11.0.1 Beta, 1.11.0.3 Beta, 1.11.4, 1.12.1, 1.12.0, 1.13.0, 1.14.1.2 Beta, 1.14.0, 1.14.30 Hotfix, 1.14.60 Hotfix, 1.16.0, 1.16.20, 1.16.50 Hotfix (iOS), 1.16.40 Hotfix, 1.16.100, 1.16.210, 1.16.221 Hotfix, 1.18.2 Hotfix, 1.19.2 Hotfix, 1.19.20, 1.19.21 Hotfix, 1.19.62