The commit fees are changing. If/when mempool fees are fluctuating, also the commit fees will increase or decrease and that will be affected in your channels "can send".
For those cases, if you really want to empty that channel, you have to go slowly with smaller amounts, going closer and closer to the last sat you can send. But with Alby Hub you cannot select a specific channel to make a payment (yet). You will need to use another node management software like Thunderhub, RTL, or Zeus that allow doing that.
Is something wrong with my LND? Should I be worried?
No. This is how LN it works. That's why we always recommend to NOT open small tiny channels where this difference can be seen easily. For a larger channel it will be insignificant change.
The commit fees are changing.
If/when mempool fees are fluctuating, also the commit fees will increase or decrease and that will be affected in your channels "can send".
Another aspect that you should take in consideration is the "buffer" kept in each channel when is about to be depleted:
https://github.com/lightningnetwork/lnd/blob/6dea86428d031171af30119e3f6599820dc5454a/lnwallet/channel.go#L3803-L3815
For those cases, if you really want to empty that channel, you have to go slowly with smaller amounts, going closer and closer to the last sat you can send.
But with Alby Hub you cannot select a specific channel to make a payment (yet). You will need to use another node management software like Thunderhub, RTL, or Zeus that allow doing that.
No. This is how LN it works. That's why we always recommend to NOT open small tiny channels where this difference can be seen easily. For a larger channel it will be insignificant change.