Elasticsearch 7.x data allocation?

I have been using the ELK stack for years, and upgraded to ELK 7 last month and updated to 7.8 last week. Previous to 7.x data allocation to my Elastic data nodes was automatically distributed among nodes to be similar. My disk mount point is the same size on all nodes, and before the 7.x upgrade, each would be around 40-50% used on each node. Now, with a healthy/green cluster they are:

node 1 - 21%
node 2 - 54%
node 3 - 14%
node 4 - 26%
node 5 - 19%
node 6 - 81%

I am accustomed to Elastic going into read-only mode when it reaches 85% full, so am cautious. Do I have anything to be concerned about?

How are the shards distributed?
/_cat/shards

Interesting. Just looked, and each node has nearly the identical number of shards. I have a small number of recent indexes that are much larger than others. Might this explain it?