ציטירנדיקער פּירוש אויף ירמיהו 22:23

וְיֹלַדְתְּ בן AND THOU SHALT BEAR A SON — The word appears to be grammatically a combination of the perfect tense וְיָלַדְתְּ and the participle וְיֹלֶדֶת but it is similar in sense to וְיֹלֶדֶת (the participle); so, also, (Jeremiah 22:23) “O thou that dwellest יֹשַׁבְתְּ) in Lebanon, and art nestled (מְקֻנַּנְתְּ) in the cedars.”

As if it were written ויולדת... I.e., יוֹלֶדֶת, which is present tense. [Rashi is saying:] Do not be surprised by the שוא under the ת, for it is similar to (Yirmeyahu 22:23):יושבת בלבנון מקוננת בארזים, which also are present tense, and have a שוא under the ת.