Ubuntu root partition takes too much space

I'm using Linux(Ubuntu 20.04) for the first time and using it as dual boot with Windows 10. I researched before I started using it. Found that there are partitions and what they are. I partitioned the SSD between the two operating systems.

I found recommended memories before downloading ubuntu:

root (/): 10-15 GB, I created it as 20 GB,

swap: 2 x RAM, so created it 16 GB,

boot: 1-2 GB, I created it as 3 GB,

home: created it as 40 GB.

But i have a problem. Ubuntu didn't start today because root memory was full!! People said 10-15 GB enough and i created it as 20 GB. I extended it to 30 GB (with GParted and ubuntu on USB) to start ubuntu. How full is it ? What is wrong with my pc or ubuntu ? Why is it filling up so fast ? What can i do to fix it ?

I have already tried:

sudo apt-get clean, sudo apt autoremove, apt-get autoremove, BleachBit..

Thank you for reading, have a nice day!!

You overpartitioned and did not give enough room for your root partition. Whatever research you did was either outdated or bad.

The minimum recommended space for Ubuntu Desktop is 25GB and has been for several years. 20GB is insufficient. Of course, it would be wise to allocate more than the bare minimum.

You do not need a swap partition. Ubuntu has used a swapfile by default, also for several years. There is no need to create a separate partition for swap.

3GB is overkill for a boot partition. You also do not need to explicitly create a separate boot partition.

You do not need a separate /home partition. Ages ago, it was easier to create a separate /home so that you could use the same home partition on different Linux distributions and/or so you could wipe and reinstall the OS and reuse the same /home. Due to the proliferation of Linux software that stores configuration files in the home folders, this is no longer as easy as it used to be. It's not recommended to create a separate /home partition and the default installation does not do this.

The default installation does not install a separate /boot, /home, or /swap because the majority of Ubuntu users do not have any use for it. If you are new to Linux or Ubuntu and you do not have a specific use case for these separate partitions, there's no need to diverge from the default installation options.

Partitions place rigid, inflexible limitations on how your space is used. Creating lots of unnecessary partitions "traps" space on your drive into sectors that are relatively inaccessible to other partitions.

Unfortunately, running out of space on your root file system is often fatal and requires a reinstall when that happens. This is because your system and software effectively "suffocate" and are unable to perform system critical writes when needed, due to lack of space.

If I were you, I would use the "Disks" application in a live session (Try Ubuntu) to delete all of your Ubuntu partitions. This will effectively delete all data on those partitions. Then, with unpartitioned free space, begin the installation and choose the guided "Install alongside Windows" option. You will have plenty of space because you will have nearly 80GB of space for Ubuntu that can be used flexibly instead of locked in a rigid inflexible partition scheme.