The gīti is an extremely rare metre, being attested in only three Pali suttas (Mettasutta, Tuvaṭakasutta, and Upālisutta) and three Jain suttas, as well as a handful of verses. It evolved to the ārya metre, which never took off in Buddhism, but became the favorite metre of the Jains.
Check out Norman’s essay.
https://www.ancient-buddhist-texts.net/Textual-Studies/Prosody-Articles/Norman-Arya.htm
How exactly, you may be wondering, is this fact “fun”?
Well, the Upālisutta is a dialogue with the Jains, and records Upāli’s conversion. And when, at the end of the sutta, he sings the Buddha’s praises, he uses the gīti metre. Thus the student of the Jains is using the metrical style that became the Jain favorite.
It seems impossible that this is just a coincidence, or that the verses were faked to create this effect. No: Upāli must have spoken these verses in this way, echoing the poetic styles of his Jain education, and applying them in praise of his new faith.