See the discussion in https://gerrit.wikimedia.org/r/c/mediawiki/services/parsoid/+/751467/1/src/Wt2Html/PP/Handlers/TableFixups.php#b276 from I0e57633b41796661565a7beb46e3309b5b0b8415
An example could be,
{| |{{1x|test | 123}} 456 |}
which is parsed as,
<table> <tbody><tr> <td>test | 123 456 </td></tr></tbody></table> <p><br />
vs
<table data-parsoid='{"dsr":[0,33,2,2]}'> <tbody data-parsoid='{"dsr":[3,31,0,0]}'><tr data-parsoid='{"autoInsertedStart":true,"dsr":[3,30,0,0]}'><td typeof="mw:Transclusion" about="#mwt1" data-parsoid='{"dsr":[3,30,1,0,1,0],"pi":[[{"k":"1"}]]}' data-mw='{"parts":["|",{"template":{"target":{"wt":"1x","href":"./Template:1x"},"params":{"1":{"wt":"test &#124; 123"}},"i":0}}," 456"]}'>123 456</td></tr> </tbody></table>