That is an interesting question.
This is an article on the results on how much of the calcium in a measure of milk that was added to various tea sources that contains oxalic acid, (which has a high propensity to bond/bond with calcium making it no longer able to be utilized by the body) bonded with oxalic acid. Scroll down to see the table with the data; the last column shows the percentage of calcium loss from the various tea sources tested. Though some sources were very low, some were relatively high in the percentage of the calcium in the milk that was lost.
http://apjcn.nhri.org.tw/server/apjcn/11/4/298.pdf
Depending upon the maturity of the teas leaves, (mature leaves) black tea leaves, tend to be higher in oxalic acid; yet compared to other leaf sources, the level of oxalic acid contained in teas were relatively lower in oxalic acid than found in (weeds) like purslane, lamb quarters, rhubarb, sorrel, etc.
Should you desire a more comprehensive list of the oxalic levels of various tea sources, you can PM me.
https://blog.piquetea.com/oxalate-in-tea/'
White tea leaves (immature leaves) tend to be higher in caffeine; black teas tend to be lower in caffeine, and green teas levels generally are in-between.