Problems encountered in the use of router-link exact

<router-link :to=""/detail/"+userID+"/"+id" class="peertab" active-class="isactive"></router-link>
<router-link :to=""/detail/"+userID+"/"+id +"/task""class="peertab" active-class="isactive"></router-link>

<a  href="-sharp/detail/3891330/6763" class="peertab isactive"></a>
<a  href="-sharp/detail/3891330/6763/task" class="peertab isactive"></a>

add exact to router-link and find that if active-class is not shown to be removed, the first one always retains active-class. Why?
do I think the corresponding is correct

Mar.03,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1beb13e-13f8c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1beb13e-13f8c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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