I have an oak tree in a mulch bed I can't keep grass out of. Can I use this 41% glyphosate in this bed without damaging the oak tree?

https://www.raganandmassey.com/compare-n-save-concentrate-grass-weed-killer-41-glyphosate.html?gclid=EAIaIQobChMIhuTuu5jX_QIVhcGGCh3S4wI5EAAYASAAEgI78_D_BwE

To start it appears the root flare is buried. If so, you gotta fix that. Then weed eat the grass to ground level, cover the area with contractors paper(HD and Lowe's carry it) and cover that with 3 inches of native cedar mulch.(NOT the dyed chipped pallet crap!) The paper will decompose naturally. Repeat every few years as needed. No chemicals necessary but you have to expose the root flare otherwise the tree will eventually die.

Do not cover the root flare!