Dvarim 9:28 reads:
פֶּן־יֹֽאמְר֗וּ הָאָרֶץ֮ אֲשֶׁ֣ר הֽוֹצֵאתָ֣נוּ מִשָּׁם֒ מִבְּלִי֙ יְכֹ֣לֶת יְהוָ֔ה לַֽהֲבִיאָ֕ם אֶל־הָאָ֖רֶץ אֲשֶׁר־דִּבֶּ֣ר לָהֶ֑ם וּמִשִּׂנְאָת֣וֹ אוֹתָ֔ם הֽוֹצִיאָ֖ם לַֽהֲמִתָ֥ם בַּמִּדְבָּֽר׃
Lest the land whence Thou broughtest us out say: Because Hashem was not able to bring them into the land which He promised unto them, and because He hated them, He hath brought them out to slay them in the wilderness.
The Torah doesn't waste words, or even letters for that matter.
If the Torah adds a seemingly extra letter (or omits one) – that's because the Torah wants to teach us something.
Why does the Torah use this round-about way when referring to Egypt here and not just say pen yomru mitzrayim... similar to Bamidbar 14:13:
וַיֹּ֥אמֶר מֹשֶׁ֖ה אֶל־יְהוָ֑ה וְשָֽׁמְע֣וּ מִצְרַ֔יִם כִּֽי־הֶעֱלִ֧יתָ בְכֹֽחֲךָ֛ אֶת־הָעָ֥ם הַזֶּ֖ה מִקִּרְבּֽוֹ׃
And Moses said unto Hashem: 'When the Egyptians shall hear – for Thou broughtest up this people in Thy might from among them.