As you say, bitcoin haven't fix this issue yet,
Who said it is an issue ?
This isn't an issue at all. It is necessary.
The adjustment each 2016 blocks is to keep a 10 minute
average.
and this was one of the fork reasons, bitcoin cash brings a solution where the difficulty changes each block.
Changing difficulty each block is a horrible approach.
Mining a block is based on luck. And in a period with 2 or 3 blocks being mined successively the algorithm would adjust the difficulty to a level which practically wouldn't be mineable anymore.
Not to mention what kind of potential for abuse this offers.
That is the reason the interval of 2 weeks (2016 blocks with a 10-minute block time) has been chosen.
To adjust fast enough to not create a death spiral and to adjust slow enough to not get affected too much from short streaks with multiple blocks caused by 'luck' or an heavily increasing hashrate.
So if you don't like bitcoin for this reason i recommend you to give a try to bch.
And lets wait to see if bitcoin take the solutions that bch brings for this issue.
An algorithm for difficulty adjustment should be a working feature (e.g. BTC). Not an issue or something 'necessary' which needs adjustments and optimization to somehow work stable (e.g. BCH).