Is saying “For God’s sake” taking the Lord’s name in vain?
Yes.
http://ww1.antiochian.org/ten-commandments
This commandment strikes at those who would not act with reverence and respect towards God’s holy name. We are forbidden to use God’s name vainly and to swear false oaths, You shall not swear by My name falsely, and so profane the name of your God (Lev. 19:12). As St. James tells us, My brethren, do not swear, either by heaven or by earth or with any other oath, but let your yes be yes and your no be no, that you may not fall under condemnation (James 5:12); this reflects the words of the Lord Himself, Who said, Let what you say be simply ‘Yes’ or ‘No’; anything more than this comes from the Evil One (Matt. 5:37). Rather, the divine name is to be glorified, for, as the Psalmist says, O Lord, our Lord, how majestic is Thy name in all the earth! (Ps. 8:1). Praise, O servants of the Lord, praise the name of the Lord! (Ps. 113:1), for the Lord’s name is blessed from this time forth and for evermore! From the rising of the sun to its setting the name of the Lord is to be praised (Ps. 113:2–3).
How often in our ordinary conversations the name of God, of Jesus (Himself God), of His Mother and of the Saints are pronounced casually, unthinkingly or even for shock effect. We moderns have such disrespect for the Holy especially for the name of God and His Son when, as St. Paul tells us, God has…bestowed on Him the name which is above every name, that at the name of Jesus every knee should bow, in heaven and on earth and under the earth (Phil. 2:9,10).
Second paragraph of this catechism really strikes at the POTUS, Pelosi, etc:
https://www.goarch.org/-/the-ten-commandments
The Third Commandment urges the faithful to use the name of the Lord With reverence and fear, but never in vain. In prayers, meditation, hymns, in teaching the Christian Truths, the faithful always use the name of God with deep devotion and respect. The faithful are instructed not to use the name of the Lord in vain. The hypocrite uses the name of the Lord in vain because he is dressing his evil thoughts with the mantle of God’s name. The Pharisee of the parable, for instance, used the name of God with a loud voice and raised his hands and eyes, but in vain. His intent was to gain arrogant personal satisfaction rather than to present a devoted prayer in repentance and humbleness.
The person who does not accept seriously the majesty of divinity, or who confesses lightly his belief and uses the name of the Lord carelessly and not with reverence and fear, uses the name of God in vain. People in high position in society who pretend they are Christians but ignore God’s commandments in their business transactions or in their homes among relatives and friends use the name of the Lord in vain. This commandment does not forbid one to take a good oath in order to establish a truth “to put an end to all strife” (Heb. 6:16). This commandment forbids the false oath and perjury.