Robin et Stella shrinking
After wishing to be tiny inside a magical Wishing Box, Stella starts shrinking smaller and smaller.
From "Robin et Stella", episode 109-111 "Le camping sauvage"
Stella dreams of joining Robin on vacation, so she makes a wish in the Wishing Box (think VR before it existed lol) to shrink small, then smaller. She figures if she's tiny enough she could join him unseen. The Box isn't supposed to actually grant wishes, but it bugs out. Thinking the machine is broken, Stella begrudgingly leaves but later starts to shrink for real! She's now doll sized and at first she's really happy, but when she shrinks a second time, closer to mouse size, she starts to panic. What if she shrinks again, and again? And disappear? She tries to get help from Robin, but his mom spots Stella and thinking she's a mouse asks Robin to get rid of her. Robin has a near miss with his huge red Converse shoe almost crushing tiny Stella.
NOTE: This one is mostly for a bit of self-indulging nostalgia as it was one of the rare shows produced in Québec that featured a shrinking girl.