Answer
Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
Answering your question, Sheikh Ahmad Kutty is a Senior Lecturer and an Islamic Scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Graves should not be overly decorated or embellished or built up. However, if the bar is erected to prevent people from trespassing or desecrating the grave, it is fine as long as it is simple; for we ought to spend our valuable resources to greater priorities.
Think of the many millions all over the world (including the Muslims of Rohingya) who suffer the worst forms of deprivation.
The money wasted on embellishing graves and planting flowers on the graves can be given in charity to them which would benefit the dead far more than any such material things.
Allah Almighty knows best.