ka le

"ka le" is the romanised Chinese words for 卡 (ka) 了 (le).

卡 = this means something is stuck or choked (hence the meaning = lag in this context)

了 = this is a word to show that the action has already happened

Therefore, ka le in Chinese means that it lagged or it is lagging.

Chinese players often say "ka le" in chat after pausing because they experience lag or other technical problems. That is where Twitch Chat caught it and turned it into a meme, especially during DAC.

It's a Gaming slung, a phrase to express "lag" from Mandarin "卡了" (ka le). First used in a Dota2 game in 2015, when some Chinese players typed it in chat to complain about their annoying game lags.

From Mandarin 卡了(ka le, "there was a lag").
usually gamer use it