I have also had this happen with Tasha, Unholy Archmage as Stormsomething#37062 commented.

Seems to effect Tasha and Davriel as well

Ran into this as well

I have also seen that this happens not only with Tamiyo, but also with Tasha, Unholy Archmage's "until your next turn" ability as well. See attached screenshots.

Update:
This bug applies to a bunch of other abilities of the form "until [time limit], whenever [condition], [effect]". You will "keep" the triggered ability until the next time the [condition] is met, even if the [time limit] has already passed.

A non-exhaustive list of cards I have observed that this issue affects: Dovin, Grand Arbiter; Mistway Spy; Davriel, Soul Broker; Tamiyo Meets the Story Circle; The Mirari Conjecture; Jace Reawakened

This issue does not seem to happen for abilities worded like "whenever [condition] this turn" like Harald Unites the Elves, The Bloodsky Massacre, or First Day of Class.

Additionally, I noticed while testing this that if you ultimate Jace Reawakened, you will only copy the first spell cast, then "lose" the ability from the ultimate even though the card says otherwise.

Occurred to me last game, please fix as soon as possible cause it is absolutely game changing

I have also run into this.